Crank-shaft construction



Aug. 12, 1930. Vca. J. MEAD 1,772,531

K SH FT I Patented Aug. 12, 1930 UNITED-f STAT-Es PAT-ENT oFFlvc-E GEORGE .1'. MEAD, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE PRATT & WHITNEY AIRCRAFT C0., 0F HARTFORD, CONNECTICUT A caux-SHAFT CONSTRUCTION Application led `October 13, 1926. Serial No. 141,356.

This invention relates in general to internal combustion engines and more particularlygto a novel type of crank shaft construction therefor.

In the designv and construction of internal combustion engines it is desirable in many cases to provide one-piece connecting rods, especially when ball or roller bearings are to be used in the large end of the connecting rod. In radial engines, where the master rod is used having a number of knuckle pins for the attachment of link rods, the conventional form of connecting rod, embodying a boltedon cap, is impractical since, in such structure, it is necessary to space the bolts widely. Such structure makes it difficult if not' sign and construction. For instance, diiculty has been experiencedin maintaining alignment of the two parts of the shaft, and

in consequence, the bearing 4surface at the large end of the connecting-rod has worn out quickly. Two-part crank shafts, as heretofore made, have lacked the essential quality of rigidity. No provision has been made for forcible separation ofthe two partsupon disassembly, and no provision has made to prevent deflection in the two parts under load stress.

It is an object'of my jinvention to provide a two-part crank shaft embodying two prink cipal component parts, which, for the purposes of identification, are designated hereinafter as the main shaft and the tail shaft. The main shaft is provided with a female crank-pin portion consisting primarily of a member having exterorly thereof a longitudinally extending connecting rod journal and interiorly thereof `a recess to receive the male portion of the crank pin, the two component members of the crank pin havin means for maintaining their alignmentv an for preventing relative rotation.

It is another object of my invention to provide means for securing together the component parts of my crank shaft in such a manner as to insure an equal distribution of load over the contacting surfaces thereof.

It is a further object of my invention to provide means for forcing apart the two component parts of the crank shaft .in disassembly.

Other objects of myinvention will appear.

in the accompanying specification and claims and will be disclosed in the accompanying drawings in which: l

-Figure 1 isl a central. vertical section through a crank shaft embodying my structure;

Figure 2 is a view similar to that shown in Figure 1, and disclosing my method of separating or forcing a art the component parts of my crank shaft uring disassembly.

Referring now with greater particularity to the drawings it will be seen that my device is comprised as followsz The main'l crank shaft 1 -is rovided with' a female crank-pin portion 3 'aving a central bore to receive the hollow male crankpin portion 4 of the tailshaft 2. Exteriorly the crank-pin portion 3 is suitably formed at 7 to provide'a bearing for the connecting rod of theengine.- The crank-pin portions 3 and 4 are provided with shoulders 5 and 6 respectively, to revent side lay of the connecting rod. divided substantially into three parts: cylindrical portions 8 andk 10, approximately onethirdof its total length, adjacent each end, and a splined portion 9 intermediate of said cylindrical portions. The tail-s aft cranke bore of t e member 3 is f pin member 4 is twice reduced in diameter member has a 'screw-threaded aperture 14 into which the screw-threaded end 15 of a clamping bolt 16 is screwed by thel rotation of its head 17.

Having reference now especially to Figure 2 it will be seen that I have provided the interior of the bore of the male crank-pin member 4, intermediate of itsends, with a threaded portion 21, the threads of which are of the same itch and the bore of which corresponds to t e diameter of the threaded end 15 of bolt 16. When it is desired to separate the two parts of the crank shaft in disassembly, the head 17 is rotated in a counterclockwise direction, and bolt 16 is withdrawn until it is free of the threads 15 and in full engagement with the threads 21. A stud 18 is then screwed into the recess 15 until the end thereof abuts the end of the bolt 16.

Further rotation of stud 18 will result in forcing the main shaft and the tail shaft apart. A suitable head 19 is provided for turning the bolt when the stress necessary to and 6 of the crank shaft sections'. The bore j of the member 7 is formed to co-act with the exterior of the-member 4 to provide the two pilot portions 11 and 13, to insure alignment of the parts of the crank-shaft while the splines 9 and 12 coact to prevent relative rotation. The bolt 16 serves to compress the parts 3 and 4 e ually, thus avoiding the misalignment whic occurs in shafts heretofore used, in which the left-hand end of the male ortion of the crank-pin is threaded and rawn in by a nut. The internal threaded portion 21 cooperates with the bolt 18 and the threaded aperture 14, to provide means for separating parts 3 and 4.

While I have shown a single-throw crank shaft, it must not be understood that my" invention is limited to such structure as it is capable of adaptation to various types of .shafts It is also within the scope of my invention to provide similarly for the joining of more than two crank shaft sections.

I claim: 1. In combination, in a two-part crank shaft, a main-shaft member having a crankpin offset, a tail-shaft member having a crank pin offset, one of said offsets being bored `to provide a female recess and the other being formed to provide a male member to lit within said recess, said female recess being provided with non-adj acent cylindricalportions, said male member being formed with cylindrical portions to fit within said female cylindrical portions to maintain said offsets in alignment, and means co-axial with said drical portions, said male member being formed with cylindrical portions to fit within said female cylindrical portions to maintain said offsets in alignment, and a bolt co-axial with said shafts bearing against one of said offsets and extending throughout the length thereof and screw-threadedly engaging with the other to hold the saine rigidly together.

3. In combinationl in a two-part crank shaft, a main-shaft member having a crank .pin offset adapted to provide a complete earing for a connecting rod, a tail-shaft member having a crank pin offset, one of said offsets being bored to provide a female recess and the other being formed to provide a male member to fit within said recess, said female recess being provided with non-ad'acent cylindrical portions, said male .mein r being formed with cylindrical portions to fit within said female cylindrical portions to main-4 tain said crank-pin offsets in alignment, and means co-axial with and extending throughout the length thereof for holding said crank-l pinofi'sets rigidly together.

4. In com ination, in a two-part crank shaft, a main-shaftv member having a crank pin offset, a tail-shaft member havin a crank pin o ifset, one of s aid offsets being ored to provide a female recess andthe other bein formed to provide a male member to fit withvin said recess, said female recess being provided with non-adjacent cylindrical portions, said male member bein formed with cylindrical portions to fit within said female cylindrical portions to maintain said offsets in alignment, splined portions intermediate of said cylindrical portions in said yoffsets adapted to engage with each other to prevent relative rotation, and 4means for holding said offsets rigidlg together.

5,. In( com ination, in a two-part crank shaft, a main-shaft member having a crank -pin offset, a tail-shaft member having a crank pin offset, one of said offsets being bored to provide a feiale recess and the other bein formed to provide a male member to fit within said'recess, said female recess being provided with non-adjacent, or spaced cylindrical portions, said male member being formed with cylindrical portions to fit Within said female cylindrical portions to maintain said offsets in alignment, splined portions intermediate of said cylindrical portions in said offsets adapted to engage with each other to preventr relative rotation,

o portions,

anda bolt bearing against one of said 'offsets and screw-threadedly engaging with the other to hold the same rigidlIy together. e,

6. n combination, in a two-part crank shaft, a main-shaft member having a crank pin offset adapted to provide a complete bearing for a connecting rod, a tail-shaft member having a crank pin offset, one of said offsets being bored to provide a female recess and the other being formed to provide a male member to fit within said recess, said female recess being provided with spaced cylindrical said male member being formed With cylindrical portions to fit within said female cylindrical portions to maintain said offsets in alignment, splined portions inter- -mediate of said cylindrical portions in said offsets adapted to engage with each other to prevent relative rotation, andv means holding said offsets rigidly together.

7. In combination, in a two-part crank shaft, a main-shaft member having a crank pin offset adapted to provide a complete bearing for a connecting rod, a tail shaft member having Aa crank pin offset, one of said offsets bein/g bored to provide a female recess and the other being formed to provide a male member to fit within said recess, said female recess being provided with spaced cylindrical portions, said male member being formedl with cylindrical portions to fit within said female cylindrical portions to maintain said offsets in alignment, splined portions intermediate of said cylindrical portions in said offsets adapted to engage with each other to prevent relative rotation, and means for holding said offsetsrigidly together. v

8. In combination, in a two-part crank shaft, a main-shaft member, a tail-shaft member, a connecting ro`d journal formed on said main shaft member, means for securing said members together, and means in said tail shaft member adapted drical portions to maintain. said offsets in alignment, splined portions .intermediate of said cylindrical portions in said offsets adapted to engage with each other to prevent relative rotation, means for holding said offsets rigidly together, and means in said tail shaft member adapted to engage with said last named means intermediate of the ends of the for to engage with said last named means intermediate of the ends of `the tail shaft member to aid in forcibly sepatail shaft memberf to aid in forcibly separrating said shaft members upon disassembly.

piece, co-axial'with said cylindrical, outer surface, the middle portion of the length of said recess being splined, and the adjacent portions toward both ends being cylindrical, another piecel of male end fitting closely into both the splines and the cylindrical portions of the recess, a bolt co-aXial with said crank pin, threaded into one of the two pieces of the crank shaft there joined, and adapted to draw them tightly together, said bolt being adapted to screw-threadedly engage the other of the two said pieces intermediate yof its ends to act as an abutment for a tool for forcing the two 'said pieces apart upon disassembly.

- 11. In combination in a two part crank shaft, a main shaft member, a tail shaft member, a connecting rod journal formed on said main shaft member, and means for securing said members together, said last-named means being adapted to screw-threadedly engage said tail shaft member intermediate of its ends to act as an abutment for a tool for the crank shaft having a forcing the two said members apart upon disassembly.

In testimony whereof I affix mjy j GEORGE si ature. M AD. 

